package com.hmdp.service.impl;

import cn.hutool.core.util.BooleanUtil;
import cn.hutool.core.util.StrUtil;
import cn.hutool.json.JSONObject;
import cn.hutool.json.JSONUtil;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.hmdp.dto.Result;
import com.hmdp.entity.Shop;
import com.hmdp.mapper.ShopMapper;
import com.hmdp.service.IShopService;
import com.hmdp.utils.CacheClient;
import com.hmdp.utils.RedisData;
import com.hmdp.utils.SystemConstants;
import org.springframework.data.geo.Distance;
import org.springframework.data.geo.GeoResult;
import org.springframework.data.geo.GeoResults;
import org.springframework.data.redis.connection.RedisGeoCommands;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.domain.geo.GeoReference;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import javax.annotation.Resource;
import java.time.LocalDateTime;
import java.util.*;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;

import static com.hmdp.utils.RedisConstants.*;

/**
 * <p>
 * 服务实现类
 * </p>
 *
 * @author 虎哥
 * @since 2021-12-22
 */
@Service
public class ShopServiceImpl extends ServiceImpl<ShopMapper, Shop> implements IShopService {

    @Resource
    private StringRedisTemplate stringRedisTemplate;
    @Resource
    private CacheClient cacheClient;

    // 获取互斥锁
    private boolean tryLock(String key) {
        Boolean flag = stringRedisTemplate.opsForValue().setIfAbsent(key, "1", LOCK_SHOP_TTL, TimeUnit.SECONDS);
        return BooleanUtil.isTrue(flag);
    }

    // 释放互斥锁
    private void unlock(String key) {
        stringRedisTemplate.delete(key);
    }

    @Override
    public Result queryById(Long id) throws InterruptedException { // 根据id查商户
        // 缓存穿透
        // Shop shop = queryWithPassThrough(id) ;
        /*// ①互斥锁解决缓存击穿
        Shop shop = queryWithMutex(id);*/
        // ②逻辑过期解决缓存击穿
        //Shop shop = queryWithLogicalExpire(id);

        // 封装工具
        // 缓存穿透
        // Shop shop = cacheClient.queryWithPassThrough(CACHE_SHOP_KEY, id, Shop.class, this::getById, CACHE_SHOP_TTL, TimeUnit.MINUTES);
        // ①互斥锁解决缓存击穿
        // Shop shop = cacheClient.queryWithMutex(CACHE_SHOP_KEY, id, Shop.class, this::getById, CACHE_SHOP_TTL, TimeUnit.MINUTES);
        // ②逻辑过期解决缓存击穿
        Shop shop = cacheClient.queryWithLogicalExpire(CACHE_SHOP_KEY, id, Shop.class, this::getById, CACHE_SHOP_TTL, TimeUnit.MINUTES);

        if (shop == null)
            return Result.fail("店铺不存在!");
        return Result.ok(shop);
    }

    // ①互斥锁
    public Shop queryWithMutex(Long id) throws InterruptedException { // 缓存击穿代码
        String key = CACHE_SHOP_KEY + id;
        // 1 . 从redis中查询商户缓存
        String shopJson = stringRedisTemplate.opsForValue().get(key);
        // 2 . 判断是否存在
        if (StrUtil.isNotBlank(shopJson)) {
            // 3 . 存在
            Shop shop = JSONUtil.toBean(shopJson, Shop.class);
            return shop;
        }
        // 判断命中的是否是空值
        if (shopJson != null) { //上面isNotBlank方法判断""和null都是返回false,因为缓存空对象为"",所以判断不是null
            // 命中空值
            // return Result.fail("店铺不存在") ;
            return null;
        }
        // 实现缓存重建
        // 4. 1 获取互斥锁
        String lockKey = LOCK_SHOP_KEY + id;
        Shop shop = null;
        try {
            boolean isLock = tryLock(lockKey);
            // 4 .2 判断是否获取成功
            if (!isLock) {
                // 4 . 3 失败 ， 则休眠并重试
                Thread.sleep(50);
                return queryWithMutex(id); // 递归重查
            }
            // 4 . 4 成功 ， 根据id查询数据库
            /*// 模拟重建的超时
            Thread.sleep(200);*/
            shop = getById(id);
            // 5 .  不存在  ， 返回错误
            if (shop == null) {
                // 将空值写入redis
                stringRedisTemplate.opsForValue().set(key, "", CACHE_NULL_TTL, TimeUnit.MINUTES);
                // 返回错误信息
                // return Result.fail("店铺不存在!") ;
                return null;
            }
            // 6 . 存在 , 写入redis
            // 加入缓存过期时间
            stringRedisTemplate.opsForValue().set(key, JSONUtil.toJsonStr(shop), CACHE_SHOP_TTL, TimeUnit.MINUTES);
        } catch (InterruptedException e) {
            throw new RuntimeException(e);
        } finally {
            // 7 . 释放互斥锁
            unlock(lockKey);
        }
        // 8 . 返回shop
        return shop;
    }

    private static final ExecutorService CACHE_REBUILD_EXECUTOR = Executors.newFixedThreadPool(10);

    // ②逻辑过期
    public Shop queryWithLogicalExpire(Long id) {
        String key = CACHE_SHOP_KEY + id;
        //1.从redis中查询商户缓存
        String shopJson = stringRedisTemplate.opsForValue().get(key);
        //2:判断是否存在
        if (StrUtil.isBlank(shopJson)) {
            //3.不存在
            return null;
        }
        // 这里不需要考虑缓存穿透
        // 4.命中，需要先把json反序列化为对象
        RedisData redisData = JSONUtil.toBean(shopJson, RedisData.class);
        Shop shop = JSONUtil.toBean((JSONObject) redisData.getData(), Shop.class);
        LocalDateTime expireTime = redisData.getExpireTime();
        // 5.判断是否过期
        if (expireTime.isAfter(LocalDateTime.now())) {
            // 5.1.未过期，直接返回店铺信息
            return shop;
        }
        // 5.2.已过期，需要缓存重建
        // 6.缓存重建
        // 6.1.获取互斥锁
        String lockKey = LOCK_SHOP_KEY + id;
        boolean isLock = tryLock(lockKey);
        // 6.2.判断是否获取锁成功
        if (isLock) {
            // 6.3成功，开启独立线程，实现缓存重建
            CACHE_REBUILD_EXECUTOR.submit(() -> {
                try {
                    //重建缓存
                    this.saveShop2Redis(id, 20L);
                } catch (Exception e) {
                    throw new RuntimeException(e);
                } finally {
                    //释放锁
                    unlock(lockKey);
                }
            });
        }
        // 6.4.返回过期的商铺信息
        return shop;
    }


    public void saveShop2Redis(Long id, Long expireSeconds) throws InterruptedException {
        // 1 . 查询店铺数据
        Shop shop = getById(id);
        /*// 压测
        Thread.sleep(200);*/
        // 2 . 封装逻辑过期时间
        RedisData redisData = new RedisData();
        redisData.setData(shop);
        redisData.setExpireTime(LocalDateTime.now().plusSeconds(expireSeconds));
        // 3 . 写入redis
        stringRedisTemplate.opsForValue().set(CACHE_SHOP_KEY + id, JSONUtil.toJsonStr(redisData));
    }

    public Shop queryWithPassThrough(Long id) {
        String key = CACHE_SHOP_KEY + id;
        //1.从redis中查询商户缓存
        String shopJson = stringRedisTemplate.opsForValue().get(key);
        //2:判断是否存在
        if (StrUtil.isNotBlank(shopJson)) {
            //3.存在
            Shop shop = JSONUtil.toBean(shopJson, Shop.class);
            return shop;
        }
        // 判断命中的是否是空值
        if (shopJson != null) { // 一定是空字符串 ， 前面isNotBlnak只有当shopJon存在且非空的情况下返回true
            // 命中空值
            return null;
        }
        //4.不存在, 根据id查询数据库
        Shop shop = getById(id);
        //4:不存在，返回错误
        if (shop == null) {
            // 解决缓存穿透
            //4.1 将空值null写入redis
            stringRedisTemplate.opsForValue().set(key, "", CACHE_NULL_TTL, TimeUnit.MINUTES);
            //4.2 返回错误信息
            return null;
        }
        //6.存在 ，写入redis
        stringRedisTemplate.opsForValue().set(key, JSONUtil.toJsonStr(shop), CACHE_SHOP_TTL, TimeUnit.MINUTES);
        return shop;
    }

    @Override
    @Transactional
    public Result update(Shop shop) {
        Long id = shop.getId();
        if (id == null) {
            return Result.fail("店铺id不能为空");
        }
        // 1 . 更新数据库
        updateById(shop);
        // 2 . 删除缓存
        stringRedisTemplate.delete(CACHE_SHOP_KEY + shop.getId());
        return Result.ok();

    }

    @Override
    public Result queryShopByType(Integer typeId, Integer current, Double x, Double y) {
        // 1 . 判断是否需要根据坐标查询
        if (x == null || y == null) {
            Page<Shop> page = query()
                    .eq("type_id", typeId)
                    .page(new Page<>(current, SystemConstants.DEFAULT_PAGE_SIZE));
            // 返回数据
            return Result.ok(page.getRecords());
        }
        // 2 . 计算分页参数
        int from = (current - 1) * SystemConstants.DEFAULT_PAGE_SIZE;
        int end = current * SystemConstants.DEFAULT_PAGE_SIZE;

        String key = SHOP_GEO_KEY + typeId;
        // 3 . 查询redis , 按照距离排序 ， 分页 ， 结果 : shopId , distance
        // GEOSEARCH key BYLONLAT x y BYRADIUS 10 WITHDISTANCE 5000
        GeoResults<RedisGeoCommands.GeoLocation<String>> results = stringRedisTemplate.opsForGeo()
                .search(
                        key,
                        GeoReference.fromCoordinate(x, y),
                        new Distance(5000),// x , y方圆5km
                        RedisGeoCommands.GeoSearchCommandArgs.newGeoSearchArgs().includeDistance()
                                .limit(end) // 0 - end 的所有
                );
        // 4 . 解析出id
        if (results == null) {
            return Result.ok(Collections.emptyList());
        }
        List<GeoResult<RedisGeoCommands.GeoLocation<String>>> resultList = results.getContent();
        // 4 . 1 截取 from - end 的部分
        List<Long> ids = new ArrayList<>(resultList.size());
        Map<String, Distance> distanceMap = new HashMap<>(resultList.size());
        if(resultList.size() <= from){
            // 没有下一页了 ， 结束
            return Result.ok(Collections.emptyList()) ;
        }
        resultList.stream().skip(from) // 跳过from前面的
                .forEach(result -> {
                    // 4 . 2 获取店铺id
                    String shopIdStr = result.getContent().getName();
                    ids.add(Long.valueOf(shopIdStr));
                    // 4 . 3 获取距离
                    Distance distance = result.getDistance();
                    distanceMap.put(shopIdStr, distance);
                });
        // 5.根据id查询Shop
        String idStr = StrUtil.join(",", ids);
        List<Shop> shops = query().in("id", ids).last("ORDER BY FIELD(id," + idStr + ")").list();
        for (Shop shop : shops) {
            shop.setDistance(distanceMap.get(shop.getId().toString()).getValue());
        }
        // 6.返回
        return Result.ok(shops);
    }
}
